<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var shuru = prompt('请输入一个网址');
(        function name() {
            var jianCe = (/^w{3}\.\w+\.com$/)
            var i = jianCe.test(shuru);
            if(i){
                console.log('www.lagou.com');
            }else{
                console.log('false')
            }
        }());
    </script>
</body>
</html>